This invention relates generally to printing or fabricating objects with pigment flakes, and more particularly to magnetically aligning pigment flakes in a plane to enhance the cumulative visual effect of the flakes.
Pigment flakes are used in a variety of applications, such as paint, inks, textiles, cosmetics, extruded films, plastic castings, and powder coatings. Different types of pigment flakes can provide various, and often striking, visual effects. Color shifting is an example of a visual effect that can be obtained using pigment flakes. The pigment flakes can have an optical interference structure, such as a Fabry-Perot structure or thin-film stack, that changes color as the flake is tilted with respect to the viewing angle. Examples of such color-shifting images are used as security features on bank notes, like the U.S. 20-dollar bill, and for decorative purposes on and in a wide variety of consumer items, including vehicles, helmets, eye glass frames, fingernail polish, and cell-phone cases, to name a few. Other examples of pigment flakes include reflective flake pigments and diffractive flake pigments.
In many applications, the pigment flakes tend to align in a plane of the object, such as the printed paper, to produce a visual optical effect from the aggregate effect of the individual flakes. It is not necessary for each flake to be perfectly aligned with each other, or with the plane of the substrate, but suitable optical effects can be obtained when a sufficient portion of the flakes are suitably aligned.
Unfortunately, some operations do not lend themselves to planar alignment of pigment flakes and others actually contribute to the degradation of alignment of flakes that are applied in a generally planar fashion. Therefore, it is desirable to produce objects incorporating pigment flakes with improved planar alignment of the flakes.